Symposium on
LMOTOR F U E L S ~ , Presented before the joint meeting of the Divisions of Gas and Fuel Chemistry and of Petroleum Chemistry a t the 9 l s t Meeting of the American Chemical Society, Kansas City, Mo., Ami1 13 t o 17. 1936
Alcohol-Gasoline as
(Continued from June, 1936, issue.)
Motor Fuel GUSTAV EGLOFF
AND
J. C. MORRELL
Universal Oil Products Company, Chicago, Ill.
A
SATISFACTORY economic structure for any nation demands that each industry bear its share without exacting aid from other industries direct or by government subsidy. Nationalism tends towards making the commonwealth a self-sustained economic unit-hence the development of motor fuels from sources other than petroleum by nations having no oil reserves and the compulsory use of alcohol-gasoline in most countries. In the United States the economic situation of the farmer has been a serious problem. A number of solutions haye been offered, among them curtailment of production, crop substitution, manufacture of industrial products from farm crops, and government subsidy. One proposal, -which is claimed by some as a panacea, is the production of alcohol from corn or other farm products grown in the United States and its use as a partial substitute for gasoline. The proposal to use alcohol in gasoline in the United States revolves in part around the arguments that (a) alcoholgasoline is a superior motor fuel, (b) there is an impending shortage of crude oil which would be conserved by the use of alcohol, (c) the use of alcohol-gasoline is economical in comparison with straight gasoline, ( d ) European experience
shows the plan t o be practical, and (e) the use of alcoholgasoline will solve the farmers economic problem. An analysis of the problem shows it to have three main aspect+-technical, economic, and political.
Technical Aspects A review of the properties of alcohol-gasoline blends and their behavior in automotive engines definitely indicates that from the standpoint of the consumer they are inferior to gasoline in most important respects. When this is considered together with the much higher cost of alcohol compared t o gasoline (37), proposals for compulsory blending, in the face of our huge domestic crude oil reserves (3), can be regarded only as an indirect and inefficient type of subsidy to agriculture a t the expense of the general public. Alcohol-gasoline blends will be considered here from the riewpoint of the ultimate consumer as well as that of the automotive engineer and chemist. The evaluation of motor fuels is a difficult matter since many factors enter into the required tests. Only trained observers can obtain with accuracy all pertinent data, see that all conditions are the same in comparative tests, and draw sound conclusions. Road tests, in particular, require extreme care in procedure; otherwise they become mere ‘(trips” through ignorance of weather conditions, accidental d e v i a t i o n s from normal performance, lack of ‘[test foresight,” and general laxity in making necessary observations.
Properties of AlcoholGasoline
&ART
OF
TESTSBY
THE
BUREAUO F
STANDARDS AND
BLENDS
In order t o make a complete analysis of the technical asp e c t s of t h e p r o b l e m , the properties of the separate components, as well as the mixture Cuurtesy, W o d d Petroleum and gasoline must be A. A . A. ON ALCOHOL-GASOLINE Of compared (Table I). 1080
SEPTEMBER, 1936 TABLE
I.
INDUSTRIAL -43D ENGINEERING CHEMISTRY
PROPERTIES O F
Alcohol-gasoline has no over-all technical advantages compared to gasoline. The increased fuel consumption of a 10 per cent alcohol-gasoline blend is approximately 4 per cent higher than gasoline alone, based on both road and block tests. The improvement in antiknock value and consequent efficiency when alcohol is added to gasoline (employing suitable design and operating conditions) is less than the decrease in efficiency as measured by fuel consumption. The over-all effect is an increased fuel consumption. The use of alcohol-gasoline introduces operating difficulties, especially in starting, acceleration, and vapor lock. The handling and shipment of alcoholgasoline are difficult because of the ease with which these components separate when traces of water are introduced. It is difficult t o keep water out of bulk or storage tanks, filling-station tanks, and mot or car tanks . The cost of alcohol-gasoline is much higher than gasoline alone; its use may have widespread detrimental effects upon our social system. The compulsory use of alcohol in gasoline in this country means that the consumer will have to pay an additional and unwarranted tax on motor fuels.
GASOLINELYD ETHYL ALCOHOL
Gasoline Calorific value (total heat of combustion:: B. t. u./lb. 21,773 B. t. u./gal. 135,000 (88) Heat of vaporization: B. t. u./lh. 129 (22) B. t. u./gal. 800 Theoretical air-vapor mixture (30 in. H g , 97 ( 5 , 85) 60' F.), B. t. u./cu. it. .Iir required for complete combustion: 196 Cu. ft./lb. 1215 Cu. ft./aal., 15 (fS, 2 5 ) Theoretical air-fuel ratio ( b y weight)
Alcohol 1" 820 (28) 84,'425 (88)
368 (22) -1,436 (28)
94.5 (25) 118
779 9 (25)
The internal combustion engine converts the heat of combustion of the fuel in part into mechanical work. Obviously, then, the fuel of lower heating value will deliver less work per gallon under the same operating conditions. Based on the heating value of alcohol and gasoline, it would require 1.6 times as much alcohol to do the same amount of work as a unit quantity of gasoline. The air-fuel ratio required for the complete combustion of alcohol is 9 : 1 by weight, while that for gasoline is 15: 1, indicating that the weight of alcohol in a unit voluine of a theoretically correct mixture is approximately 1.6 times that of the gasoline. The power output of the engine per unit J olunie of air-fuel mixture is substantially the same for alcohol and gasoline, but this is maintained only by higher consumption of alcohol its compared with gasoline.
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General Properties of Alcohol- Gasoline Blends From the data in Table I the calorific values of alcoholgasoline blends were calculated on the basis of simple mixtures. These values are reported in Table 11. Both the absolute and relative calorific values of alcohol-gasoline decrease as the percentage of alcohol increase
